Folding Saris to Filter Cholera-Contaminated Water

Rural Bangladeshi women often pour sweetened drinks through a piece of sari cloth to get rid of leaves, insects and other visible debris. But disease-causing micro-organisms are thousands of times smaller than the pores in the fabric and slip right through.

About 10 years ago, a team of researchers in Maryland and Bangladesh came up with a ridiculously simple solution: Wash and fold the sari. Four thicknesses of laundered sari fabric, with its loosened, roughened cotton fibers, will strain out most of the microscopic plankton in water. In water contaminated by cholera, enough bacilli are attached to plankton for the quantity of cholera in filtered water to drop by more than 99 percent.

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Rajesh Kumar Singh/Associated Press

Women in 27 Bangladeshi villages, where drinking water is generally scooped from a river or canal, were taught to cover the urns they used for fetching water with an old sari folded in four. Over the next 18 months the rate of cholera in these villages dropped by about 50 percent, compared with other villages — about the same effect as that achieved by a much more expensive nylon water filter.

Five years later the researchers returned to the same villages. Rates of cholera were still lower in neighborhoods where some kind of water filtering was used.

But among those women who received the original training in sari filtration, only 26 percent said they were still using even a single thickness of sari, even fewer said they were folding the cloth in four — and, when observed, fewer still were actually doing either.